Subject: Merck Team's Vaccine Could Lead To New Ways to Prevent Diseases 
Date: Published: 3/19/93 (76 lines)
Source: Wall Street Journal. Copyright Dow Jones & Co. Inc.

    Technology & Medicine:
    Merck Team's Vaccine Could Lead
    To New Ways to Prevent Diseases
    ----
    By Michael Waldholz
    Staff Reporter of The Wall Street Journal

    Scientists at Merck & Co. said they developed a new type of
 vaccine that may someday lead to a simpler and safer way to prevent
 a wide range of diseases.
    The researchers said they used the new technique to protect
 laboratory mice against a strain of the influenza virus.  The
 vaccine's effectiveness startled the scientists, who said they were
 surprised that the gene-based technique worked at all.
    "It's not just innovative, it [employs a method] scientists just
 wouldn't expect to work," said Margaret A. Liu, director of
 immunology at Merck's West Point, Pa., research facility.  "It opens
 up a whole area of research possibilities."
    In an experiment reported in today's issue of the journal
 Science, the Merck scientists led by Dr. Liu produced immunity
 against a flu virus strain by injecting the mice with bits of DNA,
 or genetic material, taken from a totally different strain of the
 flu virus.  The technique suggests that scientists may be able to
 produce a universal flu shot someday that could protect against a
 wide range of viral strains.  Currently, the flu vaccines given to
 people every autumn are altered each year because the flu virus
 circulating about the world changes annually.
    But even more important, the scientists believe the method
 employed may produce new vaccine strategies against AIDS, herpes and
 even some types of cancer.  Still, the researchers noted that much
 work must be done before they can show the technique is useful and
 safe.
    Most vaccines are made from killed or inactivated versions of a
 virus that trigger an immune reaction that can counter a viral
 invasion.  For certain diseases, how ever, this type of vaccine
 doesn't work, or is simply too dangerous to try.  Therefore, in
 recent years, scientists have developed vaccines that are made up of
 just bits of the virus, usually a protein that sits on the virus's
 outer coat.  But this strategy isn't always effective, because the
 viral coats often mutate, which is one reason the flu virus is so
 variable.
    By using a new method developed by scientists at Vical Inc., a
 biotechnology company in San Diego, the Merck researchers produced
 immunity by injecting mice with a gene from the inside of the virus
 that's conserved from strain to strain during mutations.
    Several years ago, scientists at Vical reported the surprising
 discovery that genes could be directly injected into muscle cells.
 They found that the genes then triggered the muscle cells to produce
 a protein.  Previously, scientists had thought that they needed to
 find a carrier of some sort, such as a deactivated virus, to slide a
 foreign gene into a cell.
    In the new experiment, the Merck scientists injected the mice
 with a gene that normally produces a protein deep inside the flu
 virus.  The mouse muscle cells then manufactured the virus protein on
 their surface.  Once exposed, the proteins triggered the mouse's
 immune system to make white blood cells, called killer T- cells,
 that can destroy cells infected by the flu virus.
    In the experiment, the scientists used a gene taken from one
 strain of flu virus and produced immunity against a totally
 different strain.  The scientists believe this same method might be
 employed to produce killer T-cells against HIV, the virus that
 causes AIDS, or certain cancers.
    Harriet Robinson of the University of Massachusetts Medical
 Center, Worcester, Mass., has used a similar technique to protect
 chickens against the flu virus, though that experiment has yet to be
 published.  Scientists say several other labs are racing to test the
 technique in a wide range of illnesses.

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